Notable gigs you've been to
Again along with the idea of "genre defying" and "songs that blow your mind" thread, not necessarily the best gig you've been to, but the ones that will likely be spoken about for a long time because of significance to the artist or whatnot.
First off the top of my head is Blur at Glastonbury 2009 - what they themselves have said was their best gig and most important gig. First gig back in front of a properly big crowd (after some smaller warm up shows) and they not only nailed it but put forward one of the best Glastonbury headline sets of all time. Damon was visibly nervous as hell at the start but the crowd willed him on, which helped the band take a step up, which made the crowd get behind them more and during Tender there was the biggest singalong that lasted long after the band finished, and all night long. Damon burst into tears just after "To The End". Incredible.
Could also say The Gaslight Anthem at the same festival. Playing the John Peel stage but for the first time Bruce Springsteen joined them on stage, unannounced, for a song. A surprise that genuinely nobody was expecting and although he's joined them a couple of times since, that was an "I was there" moment.
Laura Marling at the Queens Hall in 2010 (I think). Her drummer fell ill overnight and had to receive treatment hours before the show. Rather than cancel she played acoustically like she used to do at open mic nights before becoming a recording artist. She was nervous as hell and could barely speak but it was her at her absolute best, she threw in a Neil Young cover that she used to do at the open mic nights and again, one of those ones where the crowd helped the artist along and the better she got, the better the crowd got too. Again, one that's unlikely to be repeated but magical for something that was just a makeshift gig to stop having to cancel.
Sure I've got more that will come into my mind later, but what "wikipedia worthy" gigs have you been to?